05 ptcc automation overview

PTCC Automation OverviewFor Automatic Circuit Reclosers and Load Break Switches

Automation Features

Automatic Protection Group Selection

Generator Control

Automatic Change-over

Loop Automation

Automatic Protection Group Selection

Automatic Protection Group Selection (APGS) allows the appropriate Protection Group to be selected automatically without the need for operator intervention.

It works by automatically changing between Protection Groups depending on the direction of power flow.

Source Load

Forward Power Flow

Protection Group A

Reverse Power Flow

Protection Group B

Where is APGS used?

Sometimes a circuit breaker is used at a location in a supply network where the power flow can be in either direction depending on the configuration of the rest of the network.

One example of this is a network tie point where the operator may have to select a different group of protection settings to compensate for a change in power flow when changing the network configuration.

Emergency switching configurations may require more than one pair of Protection Groups.

Fdr 1

Fdr 2

The Selection Rules

Each pair of Protection Groups (A&B) (C&D) (E&F) (G&H) (I&J), contains one Primary and one Alternate Protection Group.

The number of APGS pairs depends on how many Protection Groups have been configured.

When the power flow is in the positive direction (source to load) Primary Protection Group A,C,E,G or I is used.

When the power flow is negative, Alternate Protection Group B,D,F,H or J is used.

For APGS to generate a change from Primary to Alternate Protection Group, the power flow must be >50kW in the negative direction for longer than the set period.

To Revert to Primary Protection group the power must be >50kW in the positive direction for longer than the set period.

Protection Groups

A B C D E F G H I J

Pri Alt

A B

C D

E F

G H

I J

Generator Control

Generator Control Operation

The Generator Control option can disconnect the normal source of supply when it fails and automatically start a standby generator to supply the load.

When the normal source of supply is restored, the generator is automatically shut down and the supply reconnected.

Generator start-up

Generator

IOEX

ACR

Source & Load side

LIVE

Source & Load side

DEAD

Switch

OPEN

Generator

START Request on

Generator

RUNNING

CB

Generator

IOEX

ACR

Power restoration

Generator

RUNNING

Source & Load side

LIVE

Generator

START Request off

Generator

OFF

Switch

CLOSED

CB

Summary of Operation

Starts generator Senses loss of source side supply. Isolates normal supply line. Operates generator via IOEX output. Keeps generator running till power supply

is restored.

Reverts to normal supply Senses restoration of normal supply. Turns generator off. Reconnect to normal supply.

Safety Closing of switch is disabled when

generator supply is active.

Generator Control settings

HV Dead Time Amount of time source side bushings are

“dead” before any action performed by Generator Control.

Also used to detect when the generator has stopped.

Range: 1 to 600 sec

HV Live Time Amount of time source side bushings are “live”

before any action performed by Generator Control.

Also used to detect when a generator is running.

Range: 1 to 600 sec

Control State: What Generator Control is doing.

Configuration in WSOS

Automatic Change-Over

Automatic Change-Over

The Automatic-Changeover (ACO) scheme enables supply from either of two sources in support of a single load.

This scheme is normally used in support of a critical load such as a hospital to ensure that alternate supply is always available in the

event of power failure.

Automatic Change-over Operation

Preferred Alternative

Automatic Restoration

Supply may be automatically restored using either of the following principles depending on the compatibility of the supply at each feeder.

Break Before Make In this mode the Master device will instruct

the Slave device to open and then wait until the Master switch’s load side bushings are confirmed as dead before closing itself and connecting to the load. This will cause a short interruption of supply to the load during the confirmation period.

Make Before Break In this mode the Master will close onto an

energised load and then instruct the Slave to open after confirming the presence of HV for a specified period, without interruption of supply to the load.

Make Before Break Restoration

Preferred Alternative

Break Before Make Restoration

Preferred Alternative

Automatic Change-over Communications

Preferred Alternative

Control Centre

DNP3

ACO

Auto-Changeover – Important Points

Auto-Changeover cannot be made available if other automation features are available.

Auto-Changeover can only be used when DNP3 or another suitable protocol is available.

Make Before Break can only be used for restoration when the preferred and alternative supply are compatible.

When the Auto-Changeover scheme is installed the SLAVE device must be installed, configured and checked first before the MASTER device is configured.

Loop Automation

Loop Automation – An Overview

Loop Automation is a Distributed System Automation (DSA) scheme that will restore supply to fault free sections of a network if they have been disconnected because of a fault in another section of the network.

Loop Automation can also restore the normal network configuration automatically when the faulted section is repaired.

The distributed intelligence embedded in the reclosers operates the scheme without communications or operator intervention by using the built-in voltage detection of Nu-Lec reclosers.

No additional equipment is required.

Loop Automation Operating Principal

Loop Automation reconfigures a network to restore supply to fault free sections of a network.

It achieves this through a number of steps:

Isolate faulted section.

Reconfigure network so that unfaulted sections receive supply.

Automatically restore the normal configuration when the fault is removed.

Types of Recloser

Loop Automation defines 3 “types” of reclosers. Feeder recloser

– Recloser closest to the substation. Tie recloser

– Normally Open point where two feeders meet.

Mid-point recloser

– Reclosers anywhere on network between Feeder and Tie reclosers.

TieRecloser

FeederReclosers

Mid-pointReclosers

Loop Automation re-configuration rules

Rule A: The Feeder Recloser trips when it loses

supply. Rule B:

Mid-point Reclosers changes to “B” Protection group and activates single shot mode when the source supply is lost.

Rule C: Tie Recloser closes when supply is lost on

one side only. i.e. Other supply is available.

FeederReclosers

Mid-pointReclosers

TieRecloser

Loop Automation re-configuration - Example

Rule B: Mid-point Reclosers changes to “B”

Protection group and activates single shot mode when the source supply is lost.

Rule C: Tie Recloser closes when supply is lost on

one side only. i.e. Other supply is available

FeederReclosers

Mid-pointReclosers

TieRecloser

A Prot GroupB Prot Group Single Shot

Loop Automation Restoration Rules

Rule D: The Feeder Recloser closes when source

supply is restored and it was tripped by LA, or When supply is restored on both sides.

Rule E: Mid-point Reclosers closes when supply is

restored to both sides. Rule F:

Tie Recloser trips when power flow reduces by 50%, or

Power flow direction reversal.

FeederReclosers

Mid-pointReclosers

TieRecloser

B Prot Group Single Shot

Loop Automation restoration – Mid-Point

Rule E: Mid-point Reclosers closes when

supply is restored to both sides.

FeederReclosers

Mid-pointReclosers

TieRecloser

B Prot Group Single Shot

Loop Automation restoration – Tie

Rule F: Tie Recloser trips when power flow

reduces by 50%, or Power flow direction reversal

FeederReclosers

Mid-pointReclosers

TieRecloser

A Prot GroupB Prot Group Single Shot

Supply Auto-Changeover

In addition to improving the quality of a supply in a network, Loop Automation can also be used to provide a secure supply to a critical load by implementing an Auto-Changeover (ACO) scheme.

Loop Automation as Supply Auto-Changeover

FeederRecloser

TieRecloser

Rule C:Tie Recloser closes when supply is lost on one side only. i.e. Other supply is available

Rule A:The Feeder Recloser trips when it loses supply.

Loop Automation as Supply Restoration

FeederRecloser

TieRecloser

Rule D:The Feeder Recloser closes when source supply is restored and it was tripped by LA, orWhen supply is restored on both sides

Rule F:Tie Recloser trips when power flow reduces by 50%, orPower flow direction reversal

Considerations when using Loop Automation in a Auto Change-over scheme

Advantage

No communications required between reclosers.

Disadvantage

Only Make before Break restoration is available.

Automation Overview

A couple of points to note if you are considering using automation features:

Loop Automation is a licensable feature and will only work with controllers which have their CAPM4/5 serial numbers embedded into the software.

Loop Automation, Auto Changeover and Generator Control are mutually exclusive features.